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Developmental Targeted Prevention of Conduct Disorder

Summary and Keywords

Traditionally, the term targeted prevention refers to interventions designed to prevent the development of adjustment problems in individuals by reducing risk factors or by implementing protective factors identified in studies of human development. Because risk and protective factors vary with development, a developmental perspective is necessary in order to identify which factors are most relevant at each period of life, based on well-defined and empirically supported etiological models. Moreover, because prevention strategies vary greatly depending on the factors that are targeted at different developmental periods and ages, a developmental perspective suggests that they need to be shaped accordingly. A further expansion of the concept of developmental targeted prevention includes the notion of “stepwise continuous prevention” for the extreme cases who do not revert to normative behavior during a given developmental period. This notion draws on the chronic-disease model of conduct problems and encompasses several developmental periods. The current debate around these issues is important as they apply to the prevention of conduct problems in youth by targeting risk factors during maternal pregnancy, early childhood, childhood, and adolescence. A consensual view of developmental targeted prevention is, however, necessary for prevention efforts to be coordinated and fruitful.

The term targeted prevention refers to interventions designed to prevent the development of adjustment problems in individuals by reducing risk factors or by implementing beneficial or protective factors identified in studies of human development. In the 1990s, Tremblay and Craig (1995) added a developmental perspective to the notion of targeted prevention. This added perspective has two implications: First, one needs to identify which risk or protective factors change over time and which are most relevant at each developmental period. Second, prevention strategies need to be tailored to the specific patterns of risk and protective factors which are most relevant at each developmental period. The first two parts of this chapter cover these issues in turn. The third and final part argues to include the concept of “stepwise continuous prevention” for the extreme cases who do not revert to normative behavior during a given developmental period. This concept draws on the chronic-disease model of conduct problems and encompasses several developmental periods (Kazdin, 1987).

These issues are addressed as they apply to the prevention of early-onset or persistent conduct problems and related consequences in children and adolescents. Conduct problems (i.e., aggression, opposition, rule breaking) identified as early as age 3 are the single most important personal risk factor for later violent delinquency and criminal behavior (Nagin & Tremblay, 1999). This is particularly true for the 5 to 10% of children who display conduct problems in a chronic manner (Nagin & Tremblay, 1999). These children, known as the “early starters,” account for at least half of all adolescent and adult crimes (Stattin & Magnusson, 1991). Risk factors for conduct problems and related consequences (i.e., violent delinquency and criminal offending) among early starters are well known: physical aggression, inhibitory control deficit (i.e., impulsivity), and low intelligence at the individual level; poor parental monitoring and harsh or inconsistent discipline at the family level; rejection by normative peers and affiliation with deviant friends at the peer level; norms favorable to violence and poor school climate at the school level; low income, poor housing, and high crime neighborhoods at the community level (see Farrington, 2015, for a review). The aim of all targeted prevention programs is to replace these risk factors with beneficial counterparts or to block their effects by implementing protective factors.

A Quick Historical Overview

A two-level classification system is used to classify prevention programs (Mrazek & Brown, 2002). At the first level are universal preventive interventions, in which all members of a geographical unit (e.g., a residential area, a school) or a social unit (e.g., kindergarteners, adolescents) are offered new activities or new services aimed at helping them overcome current or future challenges, but without targeting anyone in particular. According to this perspective, interventions can occur in the absence of any sign of the problem to be prevented or any visible risk, although risk for some individuals is suspected. The goal is to implement beneficial factors to facilitate healthy development. The second level includes targeted preventive interventions. In the case of targeted preventive intervention, only individuals at risk for a problem are targeted. If the individuals are at risk for environmental reasons, as in the case of children born from teenage mothers, then the targeted preventive intervention is called selective. If instead, the children are at risk on the basis of personal dispositions, such as early signs of persisting physical aggression, then the targeted preventive intervention is termed indicated. Targeted preventive interventions are deployed in the context of risk factors or early precursors of the problem to be prevented. The goal is to reduce risk factors or to implement beneficial or protective factors that might respectively counterbalance or mitigate the effects of the risk factors (more on these terms later). As can be seen, this classification lacks a developmental perspective. Without a developmental perspective, it would seem unnecessary to study proximal risk and protective factors, as well as their respective counterparts (i.e., beneficial and exacerbating or vulnerability factors) as they unfold across development (Tremblay & Craig, 1995). This would be a mistake, as argued later. Another mistake would be to compare universal and targeted prevention. These methods are equally important and complementary, although their purposes can be independent (see Vitaro & Tremblay, 2008).The present discussion focuses only on developmental targeted prevention.

Developmental targeted prevention is a series of organized, theoretically driven efforts to break the developmental pathways linking early risk factors to later adjustment problems. As illustrated in Figure 1, the disruption of this psychopathological process can be achieved through four distinct strategies: First, initial risk factors (i.e., distal risk factors), as well as their subsequent mediators (i.e., proximal risk factors), or new down-the-road risk factors (i.e., also proximal risk factors) can be eliminated. Second, beneficial factors can be implemented to compensate or counterbalance risk factors. Beneficial factors often correspond to the opposite end of risk factors. However, when the relationship between the risk factor and the negative outcome is nonlinear, the beneficial end of a factor may outweigh its negative end. This is particularly true when one pole of the relationship reaches a plateau with respect to the middle point of the continuum. For example, participants who have friends with aggression scores in the top quartile of the distribution may see their delinquency scores go up, but not participants whose friends are in the other three quartiles. In this illustration, friends’ aggression is a “pure” risk factor. Conversely, only participants with grades in the top quartile may see their delinquency scores decrease over time, not the others with scores in the other three quartiles. In this case, academic achievement is a “pure” beneficial factor (for additional examples of “pure” risk or beneficial factors, see Farrington, Ttofi, & Piquero, 2016). Third, protective factors can be put in place. The role of protective factors is to mitigate or suppress (i.e., moderate) the link between a risk factor and an outcome. Protective factors operate by interacting with the risk factor in predicting the outcome. Finally, vulnerability factors that exacerbate the impact of risk factors or reduce the impact of beneficial factors can be eliminated. Vulnerability factors are the conceptual opposite of protective factors. Both are moderators.

Figure 1. Illustration of the functions of a prevention program: to eliminate risk factors, to put in place beneficial factors (which are often the opposite ends of risk factors), to put in place protective factors, to reduce vulnerability factors (which operate as moderators).

Risk factors, mediators, and protective or vulnerability factors may vary depending on children’s age (i.e., development). Prevention strategies may vary accordingly. Therefore, we present risk or beneficial and protective or vulnerability factors in reference to four distinct, yet related, developmental periods that are particularly important in the child’s and the family’s life: (1) the perinatal period (i.e., from gestation to age 2), (2) the preschool period (i.e., from age 2 to age 5), (3) the elementary school period (i.e., from age 5 to age 12), and (4) the adolescence period (i.e., from age 12 to age 18). For each period, we examine the most relevant risk or beneficial and protective or vulnerability factors, as well as the most effective strategies to reduce or augment them.

Which Factors are Most Relevant?

Guiding Principles in Search for the Most Relevant Factors

Not all risk or beneficial factors and not all protective or vulnerability factors are equally important or relevant for developmental targeted prevention. The risk or beneficial factors and the protective or vulnerability factors that should be targeted are those that (a) are theoretically relevant and empirically active, (b) have high predictive power and high causal plausibility, (c) are potent and generative, (d) are chronologically, culturally, and geographically relevant, and (e) are modifiable in a cost-effective way. Indeed, only variables and processes that play a unique and well-documented role as main effects (for risk and beneficial factors) or moderators (for protective and vulnerability factors) in the developmental pathways leading to the emergence of maladaptation should be targeted. Hence, risk indicators with no main effect of their own such as factor A1 in Figure 2 (also called markers, proxies, or incidental correlates) need to be distinguished from risk factors with unique main effects such as factors A2, A3, and C1, mediators such as factors B1 and B2 (or C2,C3,and C4), and moderators such as factors A4 and C5. This is not an easy task given that most knowledge about risk factors is derived from correlational studies. It is, however, an important task if we want developmental targeted prevention to impact factors that make an active and possibly causal contribution to the complex chain of events leading to maladaptation. Causal plausibility is increased further when the probable mechanisms of these active factors are known. However, true causality can only be identified when controlled change in a risk or beneficial factor leads to a change in the outcome (i.e., when risk factors are experimentally manipulated).

Some risk or beneficial and protective or vulnerability factors may play an active role in a developmental pathway, and their operating mode may be well-documented, but their effect size may be small in terms of partial correlations and odds ratios resulting from multivariate analyses. These are not potent factors and may not be worth targeting through preventive efforts. Instead, priority should be given to risk or beneficial factors that are potent in terms of their effect size relative to the outcome to be prevented. Similarly, priority should be given to protective or vulnerability factors that have a high multiplicative power with respect to the link between risk and the outcome. Protective factors with buffering effects (i.e., a total mitigating effect) should be the primary target of prevention efforts, especially if risk factors are difficult to modify.

Generativity of risk or beneficial factors and of protective or vulnerability factors is also important in determining which factors deserve to be targeted. The notion of generativity refers to the number of mediators with potentially additional unique effects of their own that are triggered by a single risk or beneficial factor according to a cascade model (i.e., such as factor B1 in Figure 2). It also refers to the number of risk factors that can be moderated by a single protective factor (such as factor A4 in Figure 2) or the number of adjustment problems resulting from a single risk factor according to the principle of multi-finality described by developmental psychopathologists (Cicchetti & Hinshaw, 2002) (i.e., such as Factor C3 in Figure 2). Hence, cost-effective prevention programs should target generic risk or beneficial as well as generic moderating, either protective or exacerbating, factors to maximize their impact. Many, if not most, of these generic risk factors may be found early in life. As a result, early targeted preventive interventions during the perinatal and preschool periods may be the most (cost) effective, as results from preventive interventions during the prenatal and preschool years indicate (Aos, Lieb, Mayfield, Miller, & Pennucci, 2004).

Although important, potent, and generic, some factors may not be easily modifiable or chronologically relevant. For example, low socioeconomic status (SES) and tobacco exposure during pregnancy are independent risk factors for later conduct problems (Maughan, Taylor, Taylor, Butler, & Bynner, 2001). Low SES may be modifiable as shown by Leventhal and Brooks-Gunn (2004), but not by social or health professionals. In contrast, prenatal exposure to nicotine is more easily modifiable, at least in principle. However, modifying prenatal nicotine exposure requires the right timing; after the first months of pregnancy, it may be too late to effect change, although residual benefits may still be achieved.

To conclude, trying to change factors that cannot be changed, or when changed, do not affect the incidence of the outcome because the factors are not causal antecedents, is a waste of time and valuable resources. Trying to change factors that, although causal, are not potent, not generic, or not well-timed also proves to be a waste of resources. With these principles in mind, a recent comprehensive review by Lösel and Farrington (2012) is examined in the hope of identifying factors that meet the previously mentioned criteria. The factors covered by these authors can be grouped into five domains: individual, family, school, peer, and community. It is beyond the scope here to describe each factor in detail. Therefore, they are presented summarily, first with reference to their overarching category and next with reference to each developmental period in which they might play a role. To avoid redundancy, the focus is on beneficial and protective factors, except for “pure” risk and “pure” vulnerability factors.

Relevant Protective and Beneficial Factors

At the level of the individual, beneficial and protective factors include biological factors such as genes and neuro-physiological systems (i.e., heart rate, stress hormones). To illustrate, a functional polymorphism in the promoter region of the monoamine oxidase A (MAO-A) gene, which is relevant for normal neurotransmitter function, has been found to protect children exposed to very adverse environments from developing conduct problems and violent offending (Caspi et al., 2002). The suggested mechanism for this effect is the decreased ability of participants with low MAO-A activity to quickly degrade norepinephrine, the synaptic neurotransmitter involved in sympathetic arousal and rage. Other studies have shown that high arousal (i.e., high heart rate, high skin conductance) or a high level of the stress hormone cortisol may mitigate the association between family or community risk factors and later conduct problems, as well as the stability of conduct problems (Raine, Reynolds, Venables, & Mednick, 1997). At this moment, genes and neuro-physiological systems are not easily modifiable. Interestingly, however, they are linked to temperament-personality factors, that is, anxiety and inhibition, which have also been found to protect disruptive boys from becoming delinquent and which may be more easily modifiable through preventive interventions (Kerr, Tremblay, Pagani, & Vitaro, 1997). Other temperament-based factors such as emotional stability, sociability, positive mood, low irritability, and low impulsivity during the preschool period have been found to operate as beneficial factors in regard to later antisocial behavior. Other individual characteristics such as above-average intelligence, better executive neuropsychological functioning as manifested in self-control and social information processing, linguistic abilities, and positive cognitions toward one’s abilities and in social agencies may serve a similar beneficial function but also a protective function (Lösel & Farrington, 2012). Most temperamental dimensions and cognitive abilities are partially under genetic influence. However, they are also under environmental influence, such that the expression of the genetic factors can be altered through epigenetic mechanisms (see Vitaro, Brendgen, & Tremblay, in press). Early life experiences, in particular, may have long-lasting effects in the gene expression underlying brain function (Murgatroyd & Spengler, 2011).

At the level of the family, three categories of factors have been primarily examined as beneficial or protective: the parent-child relationship, parenting behavior, and parental social conformity. A close relationship with parents has a main effect opposite to the child’s behavior problems, that is, a beneficial effect (Stouthamer-Loeber, Loeber, Farrington, et al., 1993). This beneficial effect is already apparent during the perinatal and preschool periods in the form of maternal sensitivity (Edwards, Das Eiden, & Leonard, 2006).

During the perinatal and preschool period, family regularity (i.e., consistency of mealtime and bedtime routines) has also been found to dampen the link between a difficult temperament and the development of oppositional and aggressive behaviors (Rijlaarsdam et al., 2016). However, during childhood and adolescence, non-intrusive monitoring, consistent firm discipline, low physical punishment, high positive reinforcement for appropriate behaviors, and child’s involvement in family’s activities may prove equally important as beneficial and protective factors in regard to violence and antisocial behavior (Loeber, Farrington, Stouthamer-Loeber, & White, 2008). Parent monitoring in particular (defined as the amount of knowledge parents have regarding the activities and whereabouts of their youth) has been found to reduce risk for antisocial behavior in adolescence (van Ryzin & Dishion, 2013). This knowledge is derived from both active monitoring by the parent and the child’s willingness to disclose information (Kerr & Stattin, 2000).

Six dimensions at the school level have been examined as beneficial or protective factors: teacher-child relationship, academic achievement, school engagement, school bonding, school aspirations, and school climate. For example, a high-quality teacher–child relationship, characterized by high levels of closeness and low levels of conflict, may promote a child’s academic achievement or school engagement, which, in turn, may reduce behavior problems (Birch & Ladd, 1997; Pianta & Stuhlman, 2004). A high-quality teacher–child relationship may also prevent disruptive or aggressive children from developing trajectories of long-term externalizing and internalizing behavior problems (O’Connor, Dearing, & Collins, 2011).

High-quality teacher–child relationships may also reduce rejection by normative peers and affiliation with deviant peers, two well-known risk factors for school problems and delinquency (Buhs, Ladd, & Herald, 2006). Indeed, at the peer level, being well-accepted in the peer group and having prosocial friends have beneficial effects through modeling effects and conformity training (Vitaro, Boivin, & Bukowski, 2009). Having no friends also protects highly disruptive children from adopting delinquent behaviors but at the expense of severe internalizing problems (Brendgen, Vitaro, & Bukowski, 2000). In turn, a positive relationship with a best friend, even if the friend is aggressive, seems to have beneficial effects with respect to physical aggression in young children (Salvas et al., 2011). Contrary to the popular view, the power of friends and friendships is as strong, if not stronger, in young children than in adolescents (Boivin, Vitaro, & Poulin, 2005). Therefore, the school- and peer-related beneficial and protective factors relevant during childhood may also be relevant during the preschool period when children attend daycare or similar institutional settings (Pingault et al., 2015).

At the classroom level, descriptive and injunctive peer group norms with respect to the use of aggression have also been found to moderate the stability of aggression (Henry et al., 2000). Descriptive group norms correspond to the prevalence of a behavior, whereas injunctive norms refer to what group members are expected to do, based on the group’s level of approval or disapproval of the behavior. In a genetically informed study, results revealed that a strong genetic disposition for physical aggression in kindergarten was less likely to be expressed when peer group injunctive norms were unfavorable to such behavior than when peer group norms supported physical aggression (Brendgen, Girard, Vitaro, Dionne, & Boivin, 2013). Group norms can play an important role during each developmental period, including the preschool period.

Finally, at the community level, factors such as living in a good (middle-class) neighborhood and housing quality have been found to have both beneficial and protective effects for children at risk by virtue of personal characteristics, such as impulsivity or aggressiveness (Kupersmidt, Griesler, DeRosier, Patterson, & Davis, 1995; Lynam et al., 2000). In turn, social cohesion, informal social control, and social trust can operate as beneficial and protective factors against neighborhood poverty (Seidman et al., 1998). Again, beneficial and protective factors at the community level operate during all developmental periods, including the perinatal and the preschool periods.

The Need for a Developmental Perspective

Although many beneficial and protective factors can play an important role during different developmental periods, some may not operate in a similar way at all developmental periods. For example, after identifying behavioral risk profiles based on physical aggression, opposition, hyperactivity, inattention, and low prosociality, Fontaine and her colleagues (Fontaine, Brendgen, Vitaro, & Tremblay, 2016) examined three putative beneficial or protective factors assessed at two periods, in preadolescence (age 11 to 12 years) and at mid-adolescence (age 14 to 15 years): perceived legitimacy of legal authorities, parental monitoring, and school engagement. Four at-risk profiles and one normative profile were first identified by these authors: (1) a Low aggressive-disruptive profile (21.1%), (2) a Moderate aggressive-disruptive profile (8.1%), (3) a High aggressive-disruptive profile (7.5%), (4) a Hyperactive-inattentive profile (11.6%), and (5) a Normative profile (51.7% of the participants). As expected, participants in the first three aggressive profiles became more violent by late adolescence (16–17 years) compared to their counterparts in the Normative profile. Results also showed that perceived legitimacy of legal authorities, parental monitoring, and school engagement in mid-adolescence—but not in preadolescence—had a beneficial effect against violent delinquency in late adolescence. These beneficial effects counterbalanced—via main effects—the effects of all the behavioral risk profiles, including the High aggressive-disruptive profile. Perceived legitimacy of legal authorities, parental monitoring, and school engagement in both pre- and mid-adolescence were also identified as having a protective effect. However, these protective effects concerned only a few specific risk profiles. In particular, average levels of perceived legitimacy of legal authorities, parental monitoring, and school engagement seemed to be sufficient to prevent youth at low to moderate childhood risk from engaging in high levels of violent delinquency. However, average levels of protective effects did not seem to offset the risk of violent delinquency for High aggressive-disruptive youths.

Beneficial and protective factors also seem to vary depending on whether risk factors are defined at the individual or at the environmental level. To illustrate, Farrington and Ttofi (2012) found that factors that could help troublesome boys avoid becoming offenders, either through a beneficial or a protective effect, included a mix of individual and socio-environmental factors: high intelligence, low extraversion, low neuroticism, having few friends, parent harmony, good parental monitoring, and full-time maternal employment. In contrast, the most important factors that protected boys living in poor housing from becoming offenders were good child-rearing, small family size, good maternal discipline, high family outcome, low maternal nervousness, parent harmony, and good parental discipline, none of which referred to the children’s personal characteristics.

In sum, risk, beneficial, and protective factors can occur at the individual level, the family level, the school level, the peer level, or the community level. Like risk factors, beneficial and protective factors can operate additively (i.e., cumulatively) (Deater-Deckard, Dodge, Bates, & Pettit, 1998) or interactively (i.e., multiplicatively, synergistically) (Sameroff, Gutman, & Peck, 2003). In addition, many risk factors for delinquency are the same for males and females (Fergusson & Horwood, 2002). Finally, the number of protective and beneficial factors may need to be matched to the number of risk factors. To illustrate, some studies showed that children and adolescents who desist from serious conduct problems despite exposure to a high number of risk factors have a higher number of protective and beneficial factors than those who persist (Vanderbilt-Adriance et al., 2015). In consequence, preventive interventions may need to target several risk and beneficial or protective factors rather than just one to achieve optimal success.

Which Beneficial and Protective Factors Should be Prioritized at Each Developmental Period, and Which Preventive Interventions Should be Favored?

Cascade models can help identify the most relevant risk factors at each developmental period in reference to conduct problems. One such model has been proposed by Dodge and his colleagues (Dodge, Greenberg, Malone, & CPPRG, 2008). In examining a 13-year period (i.e., from age 5 to 18 years), these authors found that early socio-family adversity predicted harsh-inconsistent parenting, which predicted social and cognitive deficits, which predicted conduct problems, which predicted elementary school social and academic failure, which predicted parental withdrawal from supervision and monitoring, which predicted deviant peer associations, which ultimately predicted adolescent violence. Although this cascade model is linear (instead of transactional) and does not include the preschool period, it is useful to identify the most relevant risk factors at subsequent developmental periods. Unfortunately, no cascade models to our knowledge also include beneficial and protective factors. Nevertheless, some studies have identified a number of beneficial and protective factors at different periods of development, as well as strategies to effectively implement them.

At the Perinatal Period (From Gestation to Age 2)

Factors at the family level such as maternal sensitivity and family regularity should be focused on during the perinatal period because they are most proximal to the child and possibly the most modifiable. Strategies to implement these factors are also readily available and effective. A meta-analysis of the impact of 70 attachment-based interventions designed to improve maternal sensitivity concluded that the most effective interventions last between 5 and 16 sessions and are applied during the second half of the first year of life, when problems become visible but problematic parent-child relationships are not yet firmly established (Bakermans-Kranenburg, van IJzendoorn, & Juffer, 2003). However, maternal sensitivity and family regularity may not be sufficient for high-risk children and families.

The Nurse Home Visitation program first developed for the Elmira project (Olds, Sadler, & Kitzman, 2007) is a good example of a well-established program that includes crucial components targeting important beneficial or protective factors besides the ones aforementioned. In this program, a nurse visits pregnant women who have a high-risk profile. Specifically, the pregnant women are young, unmarried, and poor. Nurses visit the women on a monthly basis on average between the 24th week of pregnancy and the child’s second birthday. Nurses give support to the mothers in three areas of their life: (1) personal development, including education, workforce integration, and family planning; (2) health-related behavior, including smoking prevention and adequate nutrition for the mother and child; and (3) competent care of the child and maternal sensitivity. The nurses also link mother and child with community services. This program has been shown to reduce child abuse and neglect, as well as maternal and child delinquency in comparison to a randomly assigned control group. This program has also revealed the importance of a well-trained clinician for an effective prevention effort. In a second randomized control trial, nurses were found to have significantly greater impact on most of the outcomes studied compared to trained paraprofessionals. The outcomes ranged from reduced smoking during pregnancy and increased workforce integration among the mothers, to improved emotional and cognitive development among the children (Olds et al., 1999). Finally, results from a 19-year follow-up study showed that 25% of the children in the experimental condition were arrested, compared to 37% of the children in the control condition (Eckenrode et al., 2010). However, significant effects were limited to females.

At the Preschool Period (From Age 2 to Age 5)

In line with developmental models and results from empirical studies, children’s cognitive abilities and parents’ disciplinary skills have been the focus of most prevention programs during the preschool period (Farrington & Welsh, 2003; Piquero, Farrington, Welsh, Tremblay, & Jennings, 2009; Piquero et al., 2016). For cognitive abilities, Head Start programs for socially disadvantaged children age 3 to 5 years have been found to improve academic success in the short-term and to prevent arrests and court referrals in the long-term (Garces, Thomas, & Currie, 2002). One version of these preschool programs is most well-known, the High-Scope Perry Preschool project. This program targeted disadvantaged African American children age 3 to 4 years and included two components: (1) a daily preschool program aimed at increasing cognitive abilities, and (2) weekly home visits for a period of two years. Several long-term assessments through age 40 showed that children who participated in the program were more likely to be employed, more likely to earn higher annual incomes, more likely to have graduated from high school, and less likely to be arrested compared to the children who were part of the control group (Schweinhart, 2013).

Regarding parent training, several programs have been developed and tested among preschool-aged children (ex., Dishion’s Family Check-up: Dishion et al., 2008; Patterson’s Parent management parent training program: Patterson, 1982; Sanders’ Triple P: Sanders, Markie-Dadds, Tully, & Bor, 2000). However, the most well-known parent training program is the Incredible Years prevention program for young children with conduct problems and their families (Webster-Stratton, 1998). It is part of a comprehensive, highly structured prevention package that includes other components, each of which aims to reduce different risk factors or to implement different beneficial or protective factors. These additional components target the child and the teacher. Because the different components are related, they are described together. They were assessed within a sample of children, age 4 to 7 years, with oppositional-defiant disorder (ODD), a known precursor of conduct problems for some children. More specifically, the authors randomly assigned the children to one of the following conditions: the parent program only, the child program only, the parent and teacher programs, the child and teacher programs, and the child, parent, and teacher programs. These five conditions were compared to a waiting-list control condition.

In the parent program–only condition, the parents watched a series of 17 videotapes depicting ways parents can effectively manage problematic behaviors or situations with their children. The rationale, efficacy, and content of these weekly two-hour group training sessions at the clinic are described in detail by Webster-Stratton and colleagues (2001). The child program consisted of 18 to 19 weekly two-hour sessions with two therapists and six to seven target children. Using puppets, the therapists illustrated a series of interpersonal skills that are usually absent or in excess in ODD children’s repertoires. These included conflict resolution skills, negative attributions, perspective taking and empathy, complying with teacher or parent requests, communicating, and cooperatively playing with other children. In addition, parents and teachers were asked to reinforce the targeted skills (e.g., sharing, teamwork, friendly talk, listening, complying with requests, feeling talk, and problem solving) whenever they noticed the child using them in the home or the school. Children were also given weekly homework assignments to complete with their parents. Finally, the teacher program was composed of four full days of group training sequenced throughout the school year. Through illustrations and discussion, the teacher program promoted the use of praise and encouragement for positive behaviors, use of proactive teaching, use of incentives to motivate children, use of techniques to decrease disruptive behavior, and use of collaborative strategies with parents. The teacher workshops also included topics such as prevention of peer rejection, acknowledgement of individual differences, and strategies to prevent playground aggression. Two individual appointments with each teacher were scheduled to develop an individual behavior plan for the targeted child.

A number of studies have confirmed the power of the Incredible Years Parent Training Program to improve children’s behavior problems, on average, by improving parenting skills (Gardner, Burton, & Klimes, 2006; Webster-Stratton, 1998). However, in one study (Webster-Stratton & Hammond, 1997), parents in the parent and teacher programs reported fewer cases of behaviorally disordered children relative to the parent program-only condition, suggesting that more than one component may be necessary to achieve optimal results.

At the Elementary School Period (From Age 5 to Age 11 or 12)

Other groups of researchers have also adopted a multi-target, multi-component approach for preventing conduct problems among at-risk children. For example, the promoters of Fast Track prevention program for low socioeconomic status (SES) disruptive children and their caregivers elaborated a clear theoretical rationale for every component of their program and attached each component to specific objectives with regard to risk and protective factors (Conduct Problems Prevention Research Group [CPPRG], 1999). Each component for both the childhood and the adolescence periods of the program was first justified by the important role played by that component in the etiology of conduct disorder (the distal outcome in this study). Each component was also justified by its evidence-based effectiveness. The six components for the childhood period were: (1) group parent training aimed at improving parenting skills and parent-child interactions; (2) home visits designed to ensure that parenting skills were implemented and to inspire feelings of confidence in parents; (3) group-based social skills training with the children aimed at improving their social-cognitive skills; (4) peer-pairing, in which a target child and a no-risk peer participated in guided play sessions designed to capitalize on positive modeling from the no-risk peer and to change the no-risk peer’s likely negative perception of the target child; (5) academic tutoring designed to prevent academic problems; and (6) teacher support for effective management designed to help reduce the general level of disruptive behaviors in the classroom. As for the adolescent period, four objectives were targeted: (1) parent monitoring and positive involvement, (2) peer affiliation and peer influence, (3) academic achievement and academic orientation, and (4) social cognition and identity development. The program was implemented in four sites throughout the United States and targeted a large sample of children age 7 years who scored above the 90th percentile on the Child Behavior Checklist. The program was initially set to last a limited number of years but was eventually extended over a period of 10 years (i.e., from grade 1 through grade 10). After the first three years, the evaluation results were at best moderate with effects sizes varying between 0.2 and 0.5 with respect to teacher disruptiveness scores. After five years (by age 11 or grade 5), 37% of the randomly assigned Fast Track children had no conduct problem dysfunction compared to 27% of control children (Conduct Problems Prevention Research Group, 2002). Interestingly and importantly, mediation analyses indicated that these results were partially explained by gains in the domains targeted by the program, that is, parenting, peer relations, and social-cognitive skills. By late adolescence, the children in the prevention group were significantly better off with respect to important outcomes such as a clinical diagnosis for conduct disorder, criminal offenses, and interpersonal violence, compared to their counterparts in the control group, although the effect sizes remained moderate (CPPRG, 2005). Finally, by age 25 years, 69% of the participants in the control group manifested at least one externalized, internalized, or substance-related problem compared to 59% in the experimental group. In sum, a comprehensive, developmentally sensitive, and sustained science-based preventive intervention targeting early starters can significantly reduce adult psychopathology and violent crime for a significant number of participants but not for all of them (CPPRG, 2010).

Similar results and similar conclusions were reached by Tremblay and colleagues regarding the Montreal Experimental Longitudinal prevention program. This preventive intervention consisted of a multi-component program that targeted disruptive kindergarten boys from low socioeconomic areas when they were between 7 and 9 years old. The two-year program included a home-based parent training component and a school-based social-cognitive skills training component. Notably, the social-cognitive component was delivered at school in a small group format that included one or two target boys with three or four prosocial peers. In comparison to the control group, boys who participated in the intervention were found to have less self-reported delinquency throughout adolescence (Tremblay, Pagani-Kurtz, Mâsse, Vitaro, & Pihl, 1995) and to have fewer criminal records by 24 years of age (Boisjoli, Vitaro, Lacourse, Barker, & Tremblay, 2007). Yet, one out of five participants in the intervention group nevertheless ended up with a criminal record, compared to one in three in the control group. In addition, the intervention did not seem to influence violent crimes by age 28, although it did reduce property crimes (Vitaro, Brendgen, Giguère, & Tremblay, 2013).

These results suggest that because risk is multi-factorial, some important risk or beneficial or protective factors may not have been alleviated or even targeted by current prevention programs despite the inclusion by many of them of several components that address as many risk and protective factors in as many systems as possible. One aspect that is neglected, for example, in many of the programs is the role of behavioral norms in children’s peer group. As already noted, injunctive norms can moderate the expression of genetic liability to aggression. In turn, injunctive norms may be changed by universal programs that target the whole classroom or the whole school. It is not possible to review each program in detail, but such programs exist and have produced positive findings; for example, PATHS Curriculum to teach young children personal and interpersonal skills (Greenberg, Kusche, Cook, & Quamma, 1995), the Good Behavior Game to manage classroom behavior problems through the use of group contingencies (Petras et al., 2008), and anti-bullying campaigns that establish anti-bullying policies at the school or the district level, raise public awareness about bullying, and define roles and responsibilities for teachers, students, and parents (Salmivalli, Kärnä, & Poskiparta, 2010). This strategy illustrates how targeted and universal programs can work together. The evidence in support of the principle that “more is better,” however, is not always supported.

For example, results from the Early Risers program (August, Realmuto, Hektner, & Bloomquist, 2001) illustrate the lack of evidence in support of the notion that more is necessarily better in the context of a targeted prevention program. In their first study, August and colleagues implemented a two-year program aimed at altering the developmental trajectories of kindergarteners with early onset aggressive behavior. The Early Risers multi-component program included five CORE components: (1) a child social skills group training that used Webster-Stratton’s (1998) protocol (already described), (2) a parent education and skills training program that also used Webster-Stratton’s parent training protocol, (3) a teacher behavior management program, (4) a student mentoring program focused on academic learning, and (5) an annual six-week summer school program that included non-targeted children. In addition, it also included a FLEX family support component tailored to address the unique needs of families. Intent-to-treat analyses revealed that, compared to controls, program participants showed greater gains in social skills, academic functioning, and parent discipline, with moderate (0.26) to large (0.70) effect sizes.

In a second study, August and colleagues (August, Egan, Realmuto, & Hektner, 2003) tested whether the FLEX component increased the impact of their program as expected. The authors randomly assigned a new group of aggressive children and their families to three groups. One group received both the CORE (applied in the same manner to all participants and their families) and the FLEX (tailored to families’ specific needs) components of their Early Risers program. The second group received the CORE component only. The third group received care as usual. Implementation results showed that CORE plus FLEX participants attended more program sessions than their CORE-only counterparts. However, the experimental conditions did not differ from each other although both were superior to the care-as-usual condition in reducing children’s disruptive behaviors and parents’ levels of stress; these results suggest that the FLEX component, although intuitively appealing, did not seem to improve upon the basic CORE program.

A new and extended version of Early Risers (i.e., 3 intensive years, plus 2 booster years) significantly reduced symptoms of conduct disorder, oppositional defiant disorder, and major depressive disorder in participants by mid-adolescence compared to controls. The program’s effect on increasing social skills and parent discipline effectiveness by the end of the three intensive years (i.e., in grade 3) mediated these effects (Hektner, August, Bloomquist, Lee, & Klimes-Dougan, 2014). Yet, as in most other prevention programs, many participants manifested residual problems by mid-adolescence. More specifically, although participants reported respectively 1.81 and 1.56 fewer conduct and opposition symptoms than their control counterparts, they nevertheless still reported 5.5 conduct symptoms and 4.7 opposition symptoms on average.

At the Adolescence Period (From Age 11 or 12 to Age 18)

A possible reason for the limited impact of many, if not all, current prevention programs is their inability to set into motion sufficient mediating processes that will ensure the maintenance and possibly the progress of behavior change. The Urban Institute’s Children at Risk Program (Harrell, Cavanagh, & Sridharan, 1999) illustrates this point. Children at Risk targeted high-risk early adolescents from poor neighborhoods in five cities across the United States in an effort to prevent delinquency. The program included case management and family counseling, family skills training, academic tutoring, adult mentoring, after-school activities, and community policing. In addition, the components of the program could be adjusted depending on the specific risk factors in each neighborhood. To explain the weak and inconsistent results reported at both post-intervention and at a one-year follow-up with respect to delinquent behaviors, the authors noted that few individual, family, and community factors were changed, although some peer-related factors were (i.e., program youth affiliated with less delinquent peers and had more positive peer support). If affiliation with deviant peers was the only causal risk factor or mediator of risk factors for delinquency (i.e., both necessary and sufficient), then the Urban Institute’s Children at Risk Program should have been successful at preventing delinquency even if it failed to influence other important risk factors. As predicted by the early starter model (Moffitt, 1993) and as shown by genetically informed studies (see Vitaro, Brendgen, & Lacourse, 2015), this may not be the case. Nevertheless, peers can be protective factors, provided they possess desirable characteristics. To illustrate, Feldman and colleagues (Feldman, Caplinger, & Wodarski, 1983) showed that placing antisocial adolescents in activity groups dominated by prosocial peers resulted in reduced antisocial behavior. Other programs stress the importance not to expose at-risk youth to delinquent peers. Even if delinquent peers are not a risk factor for disruptive children to become delinquent, there is ample evidence to suggest that they can operate as facilitators (i.e., moderators). For example, Chamberlain and Reid (1998) randomly assigned male delinquents to regular group homes where they lived with other delinquent youth or to foster care families who were trained to closely supervise them in different contexts and specifically avoid contact with delinquent peers. At a one-year follow-up, the latter had fewer referrals to the justice system and reported less delinquency than the former. These positive results were replicated with a sample of delinquent girls (Leve, Chamberlain, & Reid, 2005). They are further supported by a host of studies showing the detrimental effects of deviant peer contagion in the context of prevention and intervention programs that aggregate delinquent adolescents (Dodge, Dishion, & Lansford, 2006).

A Stepwise Continuous Approach to Developmental Targeted Prevention

Most, if not all, of the previously discussed prevention programs are cost-effective (see Welsh, Farrington, & Raffan Gowar, 2015), which is good news. However, as aforementioned, none of them are effective for all cases. What can be done to improve the efficacy, and possibly the cost-effectiveness, of targeted prevention programs? One solution is to adopt a stepwise-cumulative approach that is in line with the chronic-disease model of early-onset or persistent conduct disorder proposed by Kazdin in the 1980s. Like diabetes, early-onset or persistent conduct disorder cannot be completely treated, but it can be controlled. According to this perspective, prevention programs ought to be seen as moderators of the links between risk factors and conduct disorder or as moderators of the stability of conduct disorder from one developmental period to the next (CPPRG, 2002). They could also be seen as moderators of the expression of genetic and environmental factors that are associated with conduct problems over time. For some participants, a two-year program during the perinatal period is sufficient to mitigate the stability of behavior problems or the predictive links between risk factors and early conduct problems. For those cases, prevention can be declared successful and only active surveillance is required. For others, prevention would continue until success is achieved. The continuous approach over a 10-year period adopted by the promoters of Fast Track or over a 5-year period adopted by the promoters of Early Risers is in line with the proposed approach, with one important exception: for the families and the children who become well-adjusted after a first “developmental dose of prevention”, prevention efforts would be discontinued, although booster sessions along the way may be necessary to prevent relapse in some cases. This stepwise-cumulative approach to targeted prevention utilizes the principle of the “minimally sufficient effective intervention over time” as a guiding principle (Sanders, 2012). It is also compatible with the notion of “developmental tasks,” defined as specific expectations for behavior in different social contexts at different developmental periods (Masten, Burt, & Coatsworth, 2006). Success or failure to meet these developmental tasks can be rated by parents, teachers, peers, independent observers, or the participants themselves. Success with developmental tasks specific to each developmental period would indicate success of prevention.

In this new stepwise-cumulative perspective, competing prevention programs offered at different periods would become the building blocks of an integrated prevention system. These different programs would be linked to each other at three levels. First, at the chronological level, the perinatal programs would be the first to be deployed. If the proximal results are satisfactory in terms of developmental tasks for the child and the parents, these perinatal programs would be sufficient. Participants still at risk for conduct problems after the perinatal period would be exposed to a second wave of prevention strategies during the preschool years. These may take place in the childcare setting, for example. This strategy would be repeated until the risk factors are dissipated or the protective factors are solid enough to ensure a highly probable positive trajectory. The early prevention programs should target as many potent-generic-causal factors as possible to achieve an optimal impact. However, because new risk factors may appear with development, booster programs might be needed at later transition periods to address these new and often specific risk factors. Second, at the service delivery level, different services and different personnel need to be integrated in a coherent prevention system. Triple P is a good example of a multilevel program that offers a spectrum of integrated preventive interventions tailored to each family’s needs; these interventions range from general information to intensive parent training (Sanders, 2012). Another example of a comprehensive multilevel program that offers a spectrum of integrated, developmentally sensitive preventive interventions is Fast Track, which was previously described (CPPRG, 1999). Finally, at the outcome level, it is important to acknowledge that many prevention programs target the same risk factors and use similar strategies to achieve change even though their stated intentions are to prevent different adjustment problems (e.g., school dropout vs. delinquency). As a result, programs with different stated goals may also have an important impact on other aspects of development. This, in turn, would optimize their cost-effectiveness.

In summary, developmental targeted prevention is a series of organized, theoretically driven efforts to break the developmental pathways linking early risk factors to later adjustment problems. Because the earliest risk factors are intergenerational, we adopt a stepwise cumulative approach that is in line with the chronic-disease model of conduct disorder. Like many physical health problems, conduct problems cannot be completely prevented, but they can be reduced. According to this perspective, prevention programs ought to be seen as moderators of the links between risk factors (genetic and environmental) and conduct disorder from pregnancy to adulthood. We expect that preventive intervention during pregnancy and early childhood will have the most important long-term impact. However, in many cases, if not most cases, stepwise continuous interventions (boosters) may be needed during middle childhood and adolescence to maintain or to strengthen the positive effects of the earlier interventions and to address new risk or beneficial or protective factors. Children at high risk, their parents, and their wider environments are likely to benefit from this continuous support because, as with all children, learning to control emotions and respect others is a life-long challenge. Like any theoretical proposition, a stepwise continuous approach starting during the perinatal period needs to be put to an empirical test. Relevant developmental tasks should serve as the outcomes. Finally, theoretically driven mediators should be included to ensure (a) that they are set into motion as expected and (b) that the outcomes, if positive, have been reached through mechanisms that are compatible with the strategies and the goals of the program.

Summary and Future Directions

Several prevention programs targeting early-onset or persistent conduct disorder have been developed and experimentally tested. The vast majority target risk and protective factors that are relevant at one specific developmental period. Although globally positive, their results are limited in terms of effect sizes and in terms of proportion of children or adolescents who re-enter normative developmental pathways. A stepwise cumulative prevention approach has been proposed that would combine the benefits of these different time-specific programs into an integrated developmental prevention system. This integrated developmental prevention system would start during the perinatal period and encompass as many developmental periods as necessary for individual participants and their families. Some examples of integrated developmental prevention programs exist (e.g., CPPRG, 2010; Hektner, August, Bloomquist, Lee, & Klimes-Dougan, 2014), but they are very few in number and none started at the perinatal period. Moreover, none has been compared to “traditional” targeted prevention programs that focus on one single developmental period. This is important to empirically demonstrate the added value of a stepwise cumulative prevention approach in terms of effect sizes and in terms of cost-effectiveness. Another empirical test long overdue would be to compare different prevention programs within each developmental period to select the most effective ones. Until now, most targeted prevention programs have been compared to a no-intervention control condition. Finally, and importantly, for each prevention program, researchers should document whether its components reach the anticipated goals according to the theoretically prescribed mechanisms and for whom the program is most effective. This should be done in the context of efficacy, effectiveness, and scale-up trials (Flay et al., 2005).

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